function s1_generate_a_series_of_files(){
	for i in {1..100};
	do
		echo -n $i> /tmp/new_file$i;
	done
}
function s2_list_4_files_in_long_format_about_account_and_group(){
	ls -l /etc/{passwd,shadow,group,gshadow} | sort
}
function s3_find_items_related_to_given_username(){
	grep -h $1 /etc/{passwd,shadow} | sort
}
function s4_find_items_related_to_given_group_name(){
        grep -h $1 /etc/{group,gshadow} | sort

}
function s5_create_groups_for_given_group_names(){
	groupadd rnd
	groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required(){
	useradd adam
	useradd bob
	useradd calvin
	useradd david
	useradd edward
	usermod -a -G rnd adam
	usermod -a -G rnd bob
	usermod -a -G rnd edward
	usermod -a -G itoperation calvin
	usermod -a -G itoperation david
}
function s7_change_users_shell(){
	usermod -s /usr/bin/sh adam
	usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy(){
	passwd -n 10 -x 60 -w 10 adam
	passwd -n 10 -x 60 -w 10 bob
	passwd -n 10 -x 60 -w 10 david
	passwd -n 10 -x 60 -w 10 calvin
	passwd -n 10 -x 60 -w 10 edward
}
function s9_set_password_for_five_users(){
	usernames=(adam bob calvin david edward)
	passwords=("$1" "$1" "$2" "$3" "$4" "$5")
	for((i=0;i<5;i++));
	do
		echo "${username[$i]}:${passwords[$i]}"|chpasswd
	done
}
function s10_lock_bobs_password(){
	passwd -L bob
}
function s11_include_adam_into_wheel_group(){
	sudo usermod -aG wheel adam
}
function s12_change_files_permission(){
	for((i=1;i<=100;i++));
	do
		fiename="/tmp/new_file${i}"
		if [ $((i % 3)) -eq 0 ];
		then
		sudo chmod u+rw,g+r,o-rwx "$filename";
		fi
	done
}
